1. Field of the Invention
The present invention relates primarily to sliding gate valves. More specifically it relates to that type of valve which has a submerged pour tube holder, normally fixed against movement, beneath a slide gate which in addition to being shut on and off, can be throttled. The submerged pour tube is normally totally ceramic, and extends downwardly into the pour which may be in a continuous caster mold, or which may be in a tundish when metal is teemed from a ladle to a tundish. A wide variety of submerged pour tube configurations are found in the molten metal industry, specifically due to the varying openings at the downstream portion. In some instances the exit end is open. The present invention relates to removably securing such submerged pour tubes to the tube holder portion of a sliding gate valve in such a manner as to improve the efficiency of the submerged pour tube holder and the submerged pour tube.
2. Summary of the Prior Art
Several patents relate to sliding gate valves. Exemplary is reissue U.S. Pat. No. Re. 27,723 and Ladle Gate Valve U.S. Pat. No. 4,063,668. More recently, U.S. Pat. No. 4,415,103 discloses the utilization of a submerged pour tube which is secured to the pour tube holder collector nozzle on the underneath portion of the flat upper plate portion of the submerged pour tube holder.
Further illustrative of the prior art are FIGS. 1-5. There it will be seen that the submerged pour tube C by means of mount collar D when the bolts B are secured into the mounting studs E. As shown in FIG. 2, there can be an oil canning effect when the mounting studs E pull against the lower metal portion F of the submerged pour tube holder A. This is even accentuated when the mounting stud E is located near the outer portion of the submerged pour tube holder A. Another problem which occurs is illustrated in FIG. 3 where the mounting studs E become clogged with rust, dirt, and the like which renders securing the threaded bolt B into the mounting stud E back into alignment virtually impossible without retapping the stud E. A further disadvantage is shown in FIG. 4 where it will be seen that the mounting stud E has been bent and therefore will not receive the bolt B due to misalignment. This results in having to bend or hammer the mounting stud E which can result in breakage, such as shown in FIG. 5. All of sheet 1 of drawings 1-5 are illustrative of the problems which have been addressed by the inventors.
FIG. 18 is yet another prior art design and configuration of a submerged tube holder and a submerged pour tube but with a removable connection between the bottom portion of the submerged pour tube holder, the latter comprising a collector nozzle, and the submerged pour tube. This design configuration eliminates the mounting stud problems of FIGS. 1-5 but does not materially increase the efficiency of the submerged pour tube holder, of the encompassing metal encasement of the submerged tube holder, nor of the submerged pour tube. The present invention is directed to the efficiency of the submerged pour tube holder which includes the following problems which still exist in the prior art: the cracking of the submerged pour tube due to the thermal shock, decreasing the temperature of the metal encasement so as to avoid creeping and improving the seal between the submerged pour tube and the collector nozzle and the seal between the submerged pour tube holder and the sliding gate.
In the present context it should be noted that current state of the art continuous casters have operated for more than three straight weeks, or twenty-one days, twenty-four hours per day without being shut down. To do this a throttling tundish valve having a submerged pour tube holder and submerged pour tube must be susceptible of rapid change, and must be conditioned against breakage, deformation, and also prevent aspiration of ambient air at the joint between the submerged pour tube and the collector nozzle of the submerged pour tube holder. Usually the interior bore of the submerged pour tube somewhat larger than the interior bore of the submerged pour tube holder collector nozzle creating a modest venturi effect or negative pressure area. This, in turn, can induce aspiration of ambient air at the joint. Such aspiration is to be minimized or eliminated in any proper construction of a submerged pour tube holder and its connection to a submerged pour tube.